CANBERRA, April 25 -- The arrest of a 16-year-old teenager in Sydney hours before the annual Anzac memorial services across Australia is a "truly chilling and disturbing scenario" and Australians should remain vigilant to the threat by global terrorism, said Australian Minister for Justice and Minister Assisting the Prime Minister for Counter Terrorism Michael Keenan on Monday.

"Many Australians woke to learn a 16 year old boy from Sydney was facing charges relating to the planning and preparation of a terrorist attack today on Anzac Day," the minister said in a statement.

"This is a truly chilling and disturbing scenario, and is a sad reflection of the current terror threat landscape in Australia."

He also reassured his countrypeople that the law enforcement and counter-terrorist agencies "are doing everything they can to keep our national safe".

Australian counter-terrorism authorities arrested a 16-year-old teenager at his western Sydney home late Sunday, just hours before people gathered to commemorate the nation's fallen servicemen and women on the anniversary of the World War I landings in Gallipoli in Turkey, known as the Anzac Day.

Australian Broadcasting Company (ABC) reported that the matter was heard in the Children's Court on Monday morning, and the boy did not apply for bail. Papers tendered to the court showed the teenager was allegedly trying to obtain a gun to carry out an Anzac Day terror plot, an offence that carries a maximum penalty of life imprisonment.

This is the second arrest relating to alleged terror attack at Anzac Day, a day when Australians "recognize the values forged in the past that underpin our future", said Keenan.

Five teenagers were arrested in Melbourne, along with a 14-year-old boy in Britain, for allegedly planning a terror attack at similar events last year.

"It is of great and ongoing concern that people so young remain susceptible to extremist ideologies and are willing to carry out criminal acts that attract significant penalties," Keenan said.

He urged ordinary Australians to report any suspicious act or anyone who shows signs of radicalization.

"Those who wish to do us harm -- some located here and some overseas -- continue to view Australia as a legitimate target. Families, friends and communities play a vital role in helping authorities prevent someone who may be showing signs of radicalisation from doing themselves or others harm."